1. Field of the Invention
The present invention relates to a moving apparatus having a wing portion making a flapping motion.
2. Description of the Background Art
Recently, there has been a demand for an activity of a moving apparatus such as a robot in an environment that is not well maintained beforehand and has various and many obstacles, such as human living environment or at a disaster site.
A robot having wheels for movement has been proposed (for example, in Japanese Patent Laying-Open No. 05-282040) as one of conventional moving apparatuses. Multi-joint moving apparatuses have been well studied. Further, an insect type robot having six legs for improved stability has also been developed (as disclosed, for example, in Japanese Patent Laying-Open No. 06-099369).
Further, two-leg autonomous walking robot referred to as a humanoid type robot has also been developed for improved maneuverability (as disclosed, for example, in Japanese Patent Laying-Open No. 09-272083). A robot having an endless track has also been developed (as disclosed, for example, in Japanese Patent Laying-Open No. 06-305455).
In any of these moving apparatuses, moving operation is performed while the weight of the moving apparatus itself is supported by bringing a part of the apparatus to be in contact with the ground.
A moving apparatus such as a helicopter has also been known that can move in the air while avoiding obstacles on the ground.
The conventional moving apparatuses, however, have the following problems. First, at home, there are a large number of obstacles positions of which are not fixed but changed frequently, such as family members, a pet, chairs, ornaments and toys, different from factories or offices of well-maintained environment. Further, there may be a narrow passage, stairs, or a step between rooms at home.
In the conventionally developed moving apparatuses, there is a trade-off between “ability to overcome a step” and “ability to go through a small space.” When wheels are used for moving a moving apparatus, for example, movement is achieved by friction force between the wheels and the contact surface. The friction force is in proportion to the normal drag at the contact surface.
When the radius of the wheel is D, the normal drag will be 0 at a step higher than the radius D. Therefore, friction force cannot be obtained where there is a step higher than the radius D, and hence the moving apparatus cannot overcome the step.
Therefore, when a moving apparatus having wheels that can move over every hole and corner in an environment is to be designed, the radius D of the wheel must be larger than the maximum step in the environment.
When the radius D of the wheel is increased to overcome a higher step, the ability to go through a small space lowers. Specifically, the diameter of the wheel having the radius D is 2 D, and the entire length of the moving apparatus having the wheel becomes larger than the diameter 2 D of the wheel. In order to go through a space that is bent at a right angle, it is necessary that the width of the space must be larger than about 2.81 times the radius D of the wheel.
In order to turn the moving apparatus at the site, there must be no obstacle in the area at least having four times the radius D.
Under the circumstances, applications of the conventional moving apparatuses having wheels have been limited to such an environment that has relatively small steps, for which wheels of relatively small diameter are used, or such an environment that is almost free of obstacles, for which relatively large wheels are used.
For a moving apparatus having multi-articulated joints, the length of the legs must be approximately the same as the step. For stable walking, a distance approximately the same as the length of the leg is necessary as a distance between grounding points of one leg and another. Therefore, as in the case of the moving apparatuses using wheels, the trade-off between “the ability to overcome a step” and “the ability to go through a small space” cannot be eliminated even by the moving apparatuses using legs.
In the two-leg walking robot disclosed in Japanese Patent Laying-Open No. 09-272083 as a moving apparatus, in order to go up stairs having the step of h, the maximum length of the leg must be longer than the step h. When a collapsible structure is adopted for the legs so that the size of the robot can be made smaller than the step h, the structure of the moving apparatus becomes very complicated.
Arrangement of furniture differs household by household. Even in one house, positions of chairs, for example, may be changed at meals. Namely, positions of furniture and the like are not fixed. Most pieces of the furniture are arranged on the floor.
When a moving apparatus is to be moved while avoiding such obstacles, the obstacles must be detected and a route must be searched on real time basis.
When the moving apparatus is adapted to have such a function, a detecting device, an operating device and the like occupy a large volume in the moving apparatus, hindering reduction in size of the moving apparatus. As a result, it becomes impossible for the moving apparatus to go through a small space.
At a disaster site or general field, the environment is very much different from that of a household that is relatively in order. Namely, there are unpaved roads, wasteland, field of grass, river, pond, cliff, or a hill of rubble. To move freely in such an environment has been almost impossible for conventional moving apparatuses using wheels, legs and the like.
Let us consider moving in the air to avoid obstacles. The moving apparatus such as an airplane stalls unless it is moving at a prescribed speed or higher, and hovering is not possible. Though hovering is possible for a moving apparatus such as a helicopter having a rotor, good maneuverability (speedy transition between the stationary state and the usual flight) cannot be attained because of large torque.
As described above, conventional moving apparatuses having wheels, legs or the like cannot move freely while avoiding obstacles at home or at a disaster site. Further, conventional moving apparatuses such as helicopters cannot attain superior maneuverability.